FOR 1644:  CHARON: Marine Carbonate Archives: Controls on Carbonate Precipitation and Pathways of Diagenetic Alteration

• Subject Area: Geosciences ; Medicine
• Term: from 2013 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 189839832

The DFG Forschergruppe (FOR) 1644 "CHARON" merges the skills of an interdisciplinary group of experts from various disciplines in Earth Sciences in Germany and neighbouring countries. Research fields dealt with range from marine geology, carbonate sedimentology and stratigraphy, (isotope) geochemistry, petrology, material research, petrophysics, palaeontology to numerical approaches (reactive transport modelling) and geomicrobiology. Here, we apply for phase II (2016-2019) and propose eight interconnected projects (TP) guided and supported by a coordination project (ZP0) at Bochum, Germany. TP1/Graz, Austria is submitted to both, DFG and the Austrian FWF and - if successful - will be financed by FWF according to the DACH agreement. Our aim is to continue the very successful work as performed during phase I with focus on carbonate nucleation, precipitation, and growth and the subsequent alteration of abiogenic and biogenic carbonates along diagenetic pathways. The overarching aim is to provide the community with a quantitative and process-oriented understanding of Recent to Archean carbonate archives. The importance of this research results from the fact that marine carbonates are the most important rock type for reconstructing Earth System evolution with respect to the physical, chemical, and biological evolution of the ocean as well as changes in atmospheric composition and climate dynamics. Building on phase I, five out of eight proposals will move from experimental approaches and testing to phase II application of specific proxy systems to naturally altered carbonate archives. In addition to biogenic and abiogenic carbonates (aragonite, calcite, amorphous carbonate), forming the main focus of phase I, we now add fine-grained carbonate sediments and sedimentary rocks to our study materials. Moreover, the PI's and students of three projects (TP1, 2, 5) focus on dolomites and dolomitized limestones, representing complex but common but complex archives of planet Earth. Project TP7/Göttingen contributes expert knowledge in the field of geomicrobiology and bridges the gap between thermodynamics, kinetics, and metabolic processes in the early diagenetic realm. An important strength of CHARON lies in the very close links between experimental work and field studies. Particularly, the application of sophisticated hydrothermal alteration experiments will be continued albeit with adapted and refined research questions. In combination, we cover all diagenetic domains spanning from the earlies diagenetic alteration in the presence to marine porewaters to the limits of the burial diagenetic realm into the anchimetamorphic domain. If funded, the outcome of this collaborative research project will represent a critical advance in carbonate research in general.

• DFG Programme: Research Units
• International Connection: Austria, Italy

Projects

• Assessing the significance of dolomitized limestone archives: Application and calibration of the Magnesium isotope proxy (Applicant Immenhauser, Adrian )
• Coordination Funds (Applicant Immenhauser, Adrian )
• Early diagenesis of corals generated by variable activity of endolithic algae and its impact on geochemical proxies. (Applicants Eisenhauer, Anton ;  Gorb, Stanislav N. ;  Liebetrau, Volker )
• Formation and diagenetic alteration of marine, meteoric and biogenic radiaxial calcites (Applicant Immenhauser, Adrian )
• Impact of composition and local, bulk and surface structure of fibrous carbonates on their fabric and morphology (Applicant Gies, Hermann )
• Mechanisms controlling major and trace element uptake during carbonate mineral formation and diagenetic alteration: An experimental approach (Applicant Dietzel, Martin )
• Microbial alteration of geochemical and isotope proxies in fine-grained carbonate sediments (Applicants Arp, Gernot ;  Daniel, Rolf )
• Microbially-induced carbonate precipitation and alteration in organic-rich marine sediments (Applicant Wallmann, Klaus )
• Quantification of diagenetic overprint processes of fossil carbonate skeletons derived from geological laboratories and from hydrothermal alteration experiments (Applicant Schmahl, Wolfgang W. )
• Quantitative analyses and modelling of the microstructures associated with the (hydro)thermally activated aragonite-calcite transformation in single crystals, bivalve shells, and corals (Applicants Dohmen, Ralf ;  Renner, Jörg )
• Sulfate and dolomitization - constraints for precipitation and alteration (Applicant Strauß, Harald )
• The carbonate skeleton of recent and fossil Coleoidea: Biological, physical or diagenetic control? (Applicant Mutterlose, Jörg )
• Unraveling the sulfur cycle with carbonates: mechanism of incorporation and diagenesis of structurally-substituted-sulfate (Applicant Strauß, Harald )

• Spokesperson: Professor Dr. Adrian Immenhauser